Multiple precursor showerhead with by-pass ports

ABSTRACT

A method and apparatus that includes a processing chamber that includes a showerhead with separate inlets and channels for delivering separate processing gases into a processing volume of the chamber without mixing the gases prior to entering the processing volume is provided. The showerhead includes one or more cleaning gas conduits configured to deliver a cleaning gas directly into the processing volume of the chamber while by-passing the processing gas channels. The showerhead may include a plurality of metrology ports configured to deliver a cleaning gas directly into the processing volume of the chamber while by-passing the processing gas channels. As a result, the processing chamber components can be cleaned more efficiently and effectively than by introducing cleaning gas into the chamber only through the processing gas channels.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of co-pending U.S. patentapplication Ser. No. 12/815,557, filed on Jun. 15, 2010, which claimsbenefit of U.S. Provisional Patent Application Ser. No. 61/324,271,filed Apr. 14, 2010, each of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to methods andapparatus for chemical vapor deposition (CVD) on a substrate, and, inparticular, to a showerhead design for use in metal organic chemicalvapor deposition (MOCVD) and/or hydride vapor phase epitaxy (HVPE).

2. Description of the Related Art

Group III-V films are finding greater importance in the development andfabrication of a variety of semiconductor devices, such as shortwavelength light emitting diodes (LEDs), laser diodes (LDs), andelectronic devices including high power, high frequency, hightemperature transistors and integrated circuits. For example, shortwavelength (e.g., blue/green to ultraviolet) LEDs are fabricated usingthe Group III-nitride semiconducting material gallium nitride (GaN). Ithas been observed that short wavelength LEDs fabricated using GaN canprovide significantly greater efficiencies and longer operatinglifetimes than short wavelength LEDs fabricated using non-nitridesemiconducting materials, such as Group II-VI materials.

One method that has been used for depositing Group III-nitrides, such asGaN, is metal organic chemical vapor deposition (MOCVD). This chemicalvapor deposition method is generally performed in a reactor having atemperature controlled environment to assure the stability of a firstprecursor gas which contains at least one element from Group III, suchas gallium (Ga). A second precursor gas, such as ammonia (NH₃), providesthe nitrogen needed to form a Group III-nitride. The two precursor gasesare injected into a processing zone within the reactor where they mixand move towards a heated substrate in the processing zone. A carriergas may be used to assist in the transport of the precursor gasestowards the substrate. The precursors react at the surface of the heatedsubstrate to form a Group III-nitride layer, such as GaN, on thesubstrate surface. The quality of the film depends in part upondeposition uniformity which, in turn, depends upon uniform mixing of theprecursors across the substrate.

Multiple substrates may be arranged on a substrate carrier and eachsubstrate may have a diameter ranging from 50 mm to 100 mm or larger.The uniform mixing of precursors over larger substrates and/or moresubstrates and larger deposition areas is desirable in order to increaseyield and throughput. These factors are important since they directlyaffect the cost to produce an electronic device and, thus, a devicemanufacturer's competitiveness in the marketplace.

Interaction of the precursor gases with the hot hardware components,which are often found in the processing zone of an LED or LD formingreactor, generally causes the precursors to break-down and deposit onthese hot surfaces. Typically, the hot reactor surfaces are formed byradiation from the heat sources used to heat the substrates. Thedeposition of the precursor materials on the hot surfaces can beespecially problematic when it occurs in or on the precursordistribution components, such as the showerhead. Deposition on theprecursor distribution components affects the flow distributionuniformity over time. Therefore, there is a need for a gas distributionapparatus that prevents or reduces the likelihood that the MOCVDprecursors, or HVPE precursors, are heated to a temperature that causesthem to break down and affect the performance of the gas distributiondevice. Additionally, there is a need for more effective apparatus andmethods for cleaning components of the reactor and/or precursordistribution components.

Also, as the demand for LEDs, LDs, transistors, and integrated circuitsincreases, the efficiency of depositing high quality Group-III nitridefilms takes on greater importance. Therefore, there is a need for animproved deposition apparatus and process that can provide consistentfilm quality over larger substrates and larger deposition areas.

SUMMARY OF THE INVENTION

The present invention generally provides improved methods and apparatusfor depositing Group III-nitride films using MOCVD and/or HVPEprocesses.

One embodiment of the present invention provides a showerhead apparatuscomprising a first gas channel coupled to a first gas inlet, a secondgas channel coupled to a second gas inlet, a temperature control channelcoupled to a heat exchanging system configured to supply a heatexchanging fluid through the temperature control channel, and a cleaninggas conduit extending through the first gas channel, the second gaschannel, and the temperature control channel. The first gas channel isisolated from the second gas channel, and the cleaning gas conduitdirectly couples a cleaning gas inlet to an exit surface of theshowerhead apparatus.

Another embodiment provides a substrate processing apparatus comprisinga chamber body, a substrate support, and a showerhead apparatus, whereina processing volume is defined by the chamber body, the substratesupport, and the showerhead apparatus. The showerhead apparatuscomprises a first gas channel coupled to a first gas inlet, a second gaschannel coupled to a second gas inlet, a temperature control channelcoupled to a heat exchanging system configured to supply a heatexchanging fluid through the temperature control channel, and a cleaninggas conduit extending through the first gas channel, the second gaschannel, and the temperature control channel. The first gas channel isisolated from the second gas channel and the cleaning gas conduitdirectly couples a cleaning gas inlet to the processing volume.

Yet another embodiment of the present invention provides a method ofprocessing substrates comprising introducing a first gas into aprocessing volume of a processing chamber through a first gas inletcoupled to a first gas channel of a showerhead assembly, introducing asecond gas into the processing volume of the processing chamber througha second gas inlet coupled to a second gas channel of the showerheadassembly. The first gas channel is isolated from the second gas channel.The first gas is delivered into the processing volume through aplurality of first gas conduits, and the second gas is delivered intothe processing volume through a plurality of second gas conduits. Themethod further comprises cooling the showerhead assembly by flowing aheat exchanging fluid through a temperature control channel disposed inthe showerhead assembly, wherein the plurality of first and second gasconduits are disposed through the heat exchanging channel. The methodfurther comprises introducing a cleaning gas into the processing volumeof the processing chamber through a cleaning gas conduit directlycoupling a cleaning gas inlet with the processing volume of theprocessing chamber, wherein the cleaning gas conduit extends through andis isolated from the first gas channel, the second gas channel, and thetemperature control channel.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic plan view illustrating one embodiment of aprocessing system for fabricating compound nitride semiconductor devicesaccording to embodiments described herein.

FIG. 2 is a schematic cross-sectional view of a metal-organic chemicalvapor deposition (MOCVD) chamber for fabricating compound nitridesemiconductor devices according to one embodiment of the presentinvention.

FIG. 3 is an enlarged view of detail A shown in FIG. 2.

FIG. 4 is a schematic, bottom view of the showerhead assembly shown inFIG. 2.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present invention generally provide a method andapparatus that may be utilized for deposition of Group III-nitride filmsusing MOCVD and/or HVPE precursor gases and hardware. In one embodiment,the apparatus includes a processing chamber that has a showerhead withseparate inlets and channels for delivering separate processing gasesinto a processing volume of the chamber without mixing the gases priorto entering the processing volume. In one embodiment, the showerheadincludes one or more cleaning gas conduits configured to deliver acleaning gas directly into the processing volume of the chamber whileby-passing the processing gas channels formed in the showerhead. In oneembodiment, the showerhead includes a plurality of metrology portsconfigured to deliver a cleaning gas directly into the processing volumeof the chamber while by-passing the processing gas channels formed inthe showerhead. As a result, the processing chamber components can becleaned more efficiently and effectively than by introducing cleaninggas into the chamber only through the processing gas channels.

FIG. 1 is a schematic plan view illustrating one embodiment of aprocessing system 100 that comprises the one or more MOCVD chambers 102for fabricating compound nitride semiconductor devices according toembodiments described herein. In one embodiment, the processing system100 is closed to atmosphere. The processing system 100 comprises atransfer chamber 106, a MOCVD chamber 102 coupled with the transferchamber 106, a loadlock chamber 108 coupled with the transfer chamber106, a batch loadlock chamber 109, for storing substrates, coupled withthe transfer chamber 106, and a load station 110, for loadingsubstrates, coupled with the loadlock chamber 108. The transfer chamber106 comprises a robot assembly (not shown) operable to pick up andtransfer substrates between the loadlock chamber 108, the batch loadlockchamber 109, and the MOCVD chamber 102. Although a single MOCVD chamber102 is shown, it should be understood that more than one MOCVD chamber102 or additionally, combinations of one or more MOCVD chambers 102 withone or more Hydride Vapor Phase Epitaxial (HVPE) chambers may also becoupled with the transfer chamber 106. It should also be understood thatalthough a cluster tool is shown, the embodiments described herein maybe performed using linear track systems.

In one embodiment, the transfer chamber 106 remains under vacuum duringsubstrate transfer processes. The transfer chamber vacuum level may beadjusted to match the vacuum level of the MOCVD chamber 102. Forexample, when transferring substrates from a transfer chamber 106 intothe MOCVD chamber 102 (or vice versa), the transfer chamber 106 and theMOCVD chamber 102 may be maintained at the same vacuum level. Then, whentransferring substrates from the transfer chamber 106 to the load lockchamber 108 (or vice versa) or the batch load lock chamber 109 (or viceversa), the transfer chamber vacuum level may be adjusted to match thevacuum level of the loadlock chamber 108 or batch load lock chamber 109even through the vacuum level of the loadlock chamber 108 or batch loadlock chamber 109 and the MOCVD chamber 102 may be different. Thus, thevacuum level of the transfer chamber 106 is adjustable. In certainembodiments, substrates are transferred in a high purity inert gasenvironment, such as, a high purity N₂ environment. In one embodiment,substrates transferred in an environment having greater than 90% N₂. Incertain embodiments, substrates are transferred in a high purity NH₃environment. In one embodiment, substrates are transferred in anenvironment having greater than 90% NH₃. In certain embodiments,substrates are transferred in a high purity H₂ environment. In oneembodiment, substrates are transferred in an environment having greaterthan 90% H₂.

In the processing system 100, the robot assembly (not shown) transfers asubstrate carrier plate 112 loaded with substrates into the single MOCVDchamber 102 to undergo deposition. In one embodiment, the substratecarrier plate 112 may have a diameter ranging from about 200 mm to about750 mm. The substrate carrier plate 112 may be formed from a variety ofmaterials, including SiC or SiC-coated graphite. In one embodiment, thesubstrate carrier plate 112 comprises a silicon carbide material. In oneembodiment, the substrate carrier plate 112 has a surface area of about1,000 cm² or more, preferably 2,000 cm² or more, and more preferably4,000 cm² or more. After some or all deposition steps have beencompleted, the substrate carrier plate 112 is transferred from the MOCVDchamber 102 back to the loadlock chamber 108 via the transfer robot. Inone embodiment, the substrate carrier plate 112 is then transferred tothe load station 110. In another embodiment, the substrate carrier plate112 may be stored in either the loadlock chamber 108 or the batch loadlock chamber 109 prior to further processing in the MOCVD chamber 102.One exemplary processing system 100 that may be adapted in accordancewith embodiments of the present invention is described in U.S. patentapplication Ser. No. 12/023,572, filed Jan. 31, 2008, now published asUS 2009-0194026, entitled PROCESSING SYSTEM FOR FABRICATING COMPOUNDNITRIDE SEMICONDUCTOR DEVICES, which is hereby incorporated by referencein its entirety.

In one embodiment, a system controller 160 controls activities andoperating parameters of the processing system 100. The system controller160 includes a computer processor and a computer-readable memory coupledto the processor. The processor executes system control software, suchas a computer program stored in memory. Exemplary aspects of theprocessing system 100 and methods of use adaptable to embodiments of thepresent invention are further described in U.S. patent application Ser.No. 11/404,516, filed Apr. 14, 2006, now published as U.S. 2007-024516,entitled EPITAXIAL GROWTH OF COMPOUND NITRIDE STRUCTURES, which ishereby incorporated by reference in its entirety.

FIG. 2 is a schematic cross-sectional view of the MOCVD chamber 102according to embodiments of the present invention. The MOCVD chamber 102comprises a chamber body 202, a chemical delivery module 203 fordelivering precursor gases, carrier gases, cleaning gases, and/or purgegases, a susceptor or substrate support 214, and a vacuum system 212.The chamber body 202 encloses a processing volume 208. A showerheadassembly 204 is disposed at one end of the processing volume 208, andthe substrate carrier plate 112 is disposed at the other end of theprocessing volume 208. The substrate carrier plate 112 may be disposedon the substrate support 214. The substrate support 214 has z-liftcapability for moving in a vertical direction, as shown by arrow 215. Inone embodiment, the z-lift capability may be used to move the substratesupport 214 upwardly, and closer to the showerhead assembly 204, anddownwardly, and further away from the showerhead assembly 204. In oneembodiment, the distance from the surface of the showerhead assembly 204that is adjacent the processing volume 208 to the substrate carrierplate 112 during processing ranges from about 4 mm to about 41 mm. Incertain embodiments, the substrate support 214 comprises a heatingelement (e.g., a resistive heating element (not shown)) for controllingthe temperature of the substrate support 214 and consequentlycontrolling the temperature of the substrate carrier plate 112 andsubstrates 240 positioned on the substrate carrier plate 112 and thesubstrate support 214.

In one embodiment, the showerhead assembly 204 has a first processinggas channel 204A coupled with the chemical delivery module 203 via afirst processing gas inlet 259 for delivering a first precursor or firstprocess gas mixture to the processing volume 208. In one embodiment, thechemical delivery module 203 is configured to deliver a metal organicprecursor to the first processing gas channel 204A. In one example, themetal organic precursor comprises a suitable gallium (Ga) precursor(e.g., trimethyl gallium (“TMG”), triethyl gallium (TEG)), a suitablealuminum precursor (e.g., trimethyl aluminum (“TMA”)), or a suitableindium precursor (e.g., trimethyl indium (“TMI”)).

In one embodiment, a blocker plate 255 is positioned across the firstprocessing gas channel 204A. The blocker plate 255 has a plurality oforifices 257 disposed therethrough. In one embodiment, the blocker plate255 is positioned between the first processing gas inlet 259 and thefirst processing gas channel 204A for uniformly distributing gasreceived from the chemical delivery module 203 into the first processinggas channel 204A.

In one embodiment, the showerhead assembly 204 has a second processinggas channel 204B coupled with the chemical delivery module 203 fordelivering a second precursor or second process gas mixture to theprocessing volume 208 via a second processing gas inlet 258. In oneembodiment, the chemical delivery module 203 is configured to deliver asuitable nitrogen containing processing gas, such as ammonia (NH₃) orother MOCVD or HVPE processing gas, to the second processing gas channel204B. In one embodiment, the second processing gas channel 204B isseparated from the first processing gas channel 204A by a firsthorizontal wall 276 of the showerhead assembly 204.

The showerhead assembly 204 may further include a temperature controlchannel 204C coupled with a heat exchanging system 270 for flowing aheat exchanging fluid through the showerhead assembly 204 to helpregulate the temperature of the showerhead assembly 204. Suitable heatexchanging fluids include, but are not limited to, water, water-basedethylene glycol mixtures, a perfluoropolyether (e.g., Galden® fluid),oil-based thermal transfer fluids, or similar fluids. In one embodiment,the second processing gas channel 204B is separated from the temperaturecontrol channel 204C by a second horizontal wall 277 of the showerheadassembly 204. The temperature control channel 204C may be separated fromthe processing volume 208 by a third horizontal wall 278 of theshowerhead assembly 204.

In one embodiment, the showerhead assembly 204 includes a firstmetrology assembly 291 attached to a first metrology port 296 and asecond metrology assembly 292 attached to a second metrology port 297.The first and second metrology ports 296, 297, each include a metrologyconduit 298 that is positioned in an aperture formed through theshowerhead assembly 204 and attached to the showerhead assembly 204,such as by brazing, such that each of the channels (204A, 204B, and204C) are separated and sealed from one another. The first and secondmetrology assemblies 291, 292 are used to monitor the processesperformed on the surface of the substrates 240 disposed in theprocessing volume 208 of the chamber 102. In one embodiment, the firstmetrology assembly 291 includes a temperature measurement device, suchas an optical pyrometer.

In one embodiment, the second metrology assembly 292 includes an opticalmeasurement device, such as an optical stress, or substrate bow,measurement device. Generally, the optical measurement device (notshown) includes an optical emitter, such as a light source, for emittingone or more beams of light through a sensor window disposed in thesecond metrology port 297. The beams of light are generally focusedthrough the sensor window onto a substrate 240 disposed in theprocessing volume 208 of the chamber 102. The beams of light strike thesubstrate 240 and are reflected back through the sensor window andreceived by an optical detector within the optical measurement device.The received beams of light are then compared with the emitted beams oflight to determine a property of the substrate 240, such as the amountof bow of the substrate 240 (i.e., amount of convex or concave curvatureof the upper surface of the substrate 240).

In one embodiment, the first metrology assembly 291 and the secondmetrology assembly 292 include a first gas assembly 291A and a secondgas assembly 292A, respectively, that are adapted to deliver andposition a gas from the chemical delivery module 203 through themetrology conduits 298 and into the processing volume 208 of the chamber102. In one embodiment, the chemical delivery module 203 provides apurge gas to the first and second gas assemblies 291A, 292A so as toprevent deposition of material on the surface of components within theassemblies. In one embodiment, the chemical delivery module 203 providesa cleaning gas, such as a halogen containing gas, to the first andsecond gas assemblies 291A, 292A both to clean the surface of componentswithin the assemblies and to deliver the cleaning gas directly into theprocessing volume 208 of the chamber 102 to clean components of thechamber 102 without being distributed through the first processing gaschannel 204A or the second processing gas channel 204B. In oneembodiment, the showerhead assembly 204 has a plurality of firstmetrology ports 296 and/or a plurality of second metrology ports 297,and the showerhead assembly 204 has a respective plurality of firstand/or second metrology assemblies 291, 292 and first and/or second gasassemblies 291A, 292A attached thereto, respectively.

In certain embodiments, the showerhead assembly 204 includes one or morecleaning gas conduits 204D coupled with the chemical delivery module 203via a cleaning gas inlet 260 for delivering a cleaning gas, such as ahalogen containing gas, directly through the showerhead assembly 204 andinto the processing volume 208 without being distributed through thefirst processing gas channel 204A or the second processing gas channel204B. In one embodiment, the chemical delivery module 203 is configuredto deliver a cleaning gas, such as fluorine (F₂) gas, chlorine (Cl₂)gas, bromine (Br₂) gas, and iodine (I₂) gas through the one or morecleaning gas conduits 204D, and/or the metrology conduits 298, directlyinto the processing volume 208 of the chamber 102. In anotherembodiment, the chemical delivery module 203 is configured to deliver acleaning gas comprising hydrogen iodide (HI), hydrogen chloride (HCl),hydrogen bromide (HBr), hydrogen fluoride (HF), nitrogen trifluoride(NF₃), and/or other similar gases. In one embodiment, diatomic chlorine(Cl₂) gas is used as the cleaning gas. In another embodiment, diatomicfluorine (F₂) gas is used as the cleaning gas. In one embodiment, afterentering the processing volume 208, the cleaning gas is distributedthereabout, to remove deposits from chamber components, such as thesubstrate support 214, the surface of the showerhead assembly 204, andthe walls of the chamber body 202, and removed from the chamber 102 viaexhaust ports 209, which are disposed about an annular exhaust channel205 disposed within walls of the chamber body 202. In anotherembodiment, a remote plasma source 226 may be provided to generateplasma from the cleaning gas received from the chemical delivery module203 to be flowed into the processing volume 208 of the chamber 102 forcleaning the components thereof.

FIG. 3 is an enlarged view of detail A shown in FIG. 2. Referring toFIGS. 2 and 3, in one embodiment, the first precursor or firstprocessing gas mixture, such as a metal organic precursor, is deliveredfrom the first processing gas channel 204A through the second processinggas channel 204B and the temperature control channel 204C into theprocessing volume 208 via a plurality of inner gas conduits 246. Theinner gas conduits 246 may be cylindrical tubes located within alignedholes disposed through the first horizontal wall 276, the secondhorizontal wall 277, and the third horizontal wall 278 of the showerheadassembly 204. In one embodiment, the inner gas conduits 246 are eachattached to the first horizontal wall 276 of the showerhead assembly 204by suitable means, such as brazing.

In one embodiment, the second precursor or second processing gasmixture, such as a nitrogen precursor, is delivered from the secondprocessing gas channel 204B through the temperature control channel 204Cand into the processing volume 208 via a plurality of outer gas conduits245. The outer gas conduits 245 may be cylindrical tubes each locatedconcentrically about a respective inner gas conduit 246. The outer gasconduits 245 are located within the aligned holes disposed through thesecond horizontal wall 277 and the third horizontal wall 278 of theshowerhead assembly 204. In one embodiment, the outer gas conduits 245are each attached to the second horizontal wall 277 of the showerheadassembly 204 by suitable means, such as brazing.

Periodically, it is desirable to clean the components of the chamber 102between deposition processes. In one embodiment, a cleaning gas isdelivered from the chemical delivery module 203 through the firstprocessing gas channel 204A, the second processing gas channel 204B, andthe temperature control channel 204C via the one or more cleaning gasinlets 260 and cleaning gas conduits 204D and into the processing volume208 of the chamber 102. Each cleaning gas conduit 204D may be acylindrical tube located within aligned holes disposed through a tophorizontal wall 279, the first horizontal wall 276, the secondhorizontal wall 277, and the third horizontal wall 278 of the showerheadassembly 204. In one embodiment, each cleaning gas conduit 204D isattached to the first horizontal wall 276, the second horizontal wall277, and the third horizontal wall 278 of the showerhead assembly 204 bysuitable means, such as brazing, such that each of the channels (204A,204B, and 204C) of the showerhead assembly are separated and isolatedfrom one another.

In one embodiment, the showerhead assembly 204 may contain a singlecleaning gas conduit 204D located at a central point in the showerheadassembly 204 as shown in FIGS. 2 and 3. In one embodiment, theshowerhead assembly 204 may contain additional cleaning gas conduits204D located at various locations within the showerhead assembly 204.

In one embodiment, the cleaning gas is further distributed through thefirst processing gas channel 204A and/or second processing gas channel204B through their respective gas inlets (259, 258). The cleaning gas isthen routed through inner gas conduits 246 and/or outer gas conduits245, respectively. In such an embodiment, the cleaning gas reacts withdeposits and/or precursor gases within the first and/or or secondprocessing gas channels (204A, 204B) and inner and/or outer gas conduits(246, 245) to clean the respective regions within the showerheadassembly 204. However, a substantial portion of the cleaning gas hasalready reacted with the particles and/or gases within the showerheadassembly 204 by the time it reaches the processing volume 208 of thechamber 102. Thus, because the cleaning gas has been scavenged by thetime it reaches the processing volume 208, cleaning components that arein contact with the processing volume 208 only through the processinggas passages is relatively time consuming, inefficient, and ineffective.

As previously described, embodiments of the present invention directsthe cleaning gas directly through the showerhead assembly 204 via thecleaning gas conduit 204D, and/or the metrology conduits 298, whichby-pass the first and second processing gas channels (204A, 204B). As aresult, the highly reactive cleaning gas is distributed into and aboutthe processing volume 208 prior to reacting with deposits and precursorgases located within the showerhead assembly 204. This enables moreefficient and direct cleaning of components within the processing volume208, such as the substrate support 214, the surface of the showerheadassembly 204, and the chamber body 202 than if the cleaning gas wereonly distributed through the first and second processing gas channels(204A, 204B) and gas conduits (246, 245) of the showerhead assembly 204.In one embodiment, a cleaning gas that is delivered through the cleaninggas conduit 204D, and/or the metrology conduits 298, is used to directlyclean the surface of one or more substrates 240, which are disposed inthe processing volume 208, prior to depositing a layer thereon (e.g.,Group III-nitride film). In another embodiment, a cleaning gas that isdelivered through the cleaning gas conduit 204D, and/or the metrologyconduits 298, is used to directly clean an empty carrier plate 112 thatis disposed in the processing volume 208, to remove any unwanteddeposited material (e.g., Group III-nitride film) disposed thereon.Thus, by delivering the cleaning gas directly through the showerhead andby-passing the processing gas distribution channels, the components ofthe processing chamber are efficiently cleaned while reducing scavengingeffects that would be associated with delivering cleaning gases onlythrough showerhead processing gas passages.

In one embodiment, each processing chamber 102 may be cleaned after thedeposition of the Group III-nitride film on one or more of thesubstrates 240 that are disposed on a first carrier plate 112, and priorto insertion of a second carrier plate 112 containing a second set ofone or more substrates 240. In one embodiment, the chamber components ineach processing chamber 102 may be cleaned periodically. In oneembodiment, the frequency and/or duration of each cleaning may bedetermined based on the thickness of each layer deposited. For example,a cleaning process performed after deposition of a thin layer is shorterthan a cleaning process performed after deposition of a thicker layer.In one example, a first processing chamber 102 may be cleaned after eachu-GaN and n-GaN deposition process. In one embodiment, the processingchamber 102 may be cleaned periodically, for example after 50 depositioncycles. In one embodiment, another processing chamber 102 may be cleanedafter the removal of each carrier plate 112.

FIG. 4 is a schematic, bottom view of the showerhead assembly 204 shownin FIG. 2 according to one embodiment of the invention. In oneembodiment, the showerhead assembly 204 includes the cleaning gasconduit 204D positioned at the center of the showerhead assembly 204 anda plurality of first and second metrology assemblies 296, 297 arrangedin a concentric pattern about the cleaning gas conduit 204D. In oneembodiment, the first and second metrology assemblies 296, 297 arepositioned such that they are centered over a central portion of thesubstrates 240 (FIG. 2) disposed on the carrier plate 112 (FIG. 2) as itis rotated during processing.

Referring back to FIG. 2, a lower dome 219 is disposed at one end of alower volume 210, and the substrate carrier plate 112 is disposed at theother end of the lower volume 210. The substrate carrier plate 112 isshown in an elevated, process position, but may be moved to a lowerposition where, for example, the substrates 240 may be loaded orunloaded. An exhaust ring 220 may be disposed around the periphery ofthe substrate carrier plate 112 to help prevent deposition fromoccurring in the lower volume 210 and also help direct exhaust gasesfrom the chamber 102 to the exhaust ports 209. The lower dome 219 may bemade of transparent material, such as high-purity quartz, to allow lightto pass through for radiant heating of the substrates 240. The radiantheating may be provided by a plurality of inner lamps 221A and outerlamps 221B disposed below the lower dome 219. Reflectors 266 may be usedto help control exposure of the chamber 102 to the radiant energyprovided by the inner and outer lamps 221A, 221B. Additional rings oflamps (not shown) may also be used for finer temperature control of thesubstrates 240.

In certain embodiments of the present invention, a purge gas (e.g., anitrogen containing gas) is delivered into the chamber 102 from theshowerhead assembly 204 through one or more purge gas channels 281coupled to a purge gas source 282. In this embodiment, the purge gas isdistributed through a plurality of orifices 284 about the periphery ofthe showerhead assembly 204. The plurality of orifices 284 may beconfigured in a circular pattern about the periphery of the showerheadassembly 204 and positioned distribute the purge gas about the peripheryof the substrate carrier plate 112 to prevent undesirable deposition onedges of the substrate carrier plate 112, the showerhead assembly 204,and other components of the chamber 102, which result in particleformation and, ultimately contamination of the substrates 240. The purgegas flows downwardly into multiple exhaust ports 209, which are disposedaround the annular exhaust channel 205. An exhaust conduit 206 connectsthe annular exhaust channel 205 to a vacuum system 212, which includes avacuum pump 207. The pressure of the chamber 102 may be controlled usinga valve system, which controls the rate at which the exhaust gases aredrawn from the annular exhaust channel 205.

In other embodiments, purge gas tubes 283 are disposed near the bottomof the chamber body 102. In this configuration, the purge gas enters thelower volume 210 of the chamber 102 and flows upwardly past thesubstrate carrier plate 112 and exhaust ring 220 and into the multipleexhaust ports 209.

The chemical delivery module 203 supplies chemicals to the MOCVD chamber102. Reactive gases (e.g., first and second precursor gases), carriergases, purge gases, and cleaning gases may be supplied from the chemicaldelivery system through supply lines and into the chamber 102. In oneembodiment, the gases are supplied through supply lines and into a gasmixing box where they are mixed together and delivered to the showerheadassembly 204. Generally supply lines for each of the gases includeshut-off valves that can be used to automatically or manually shut-offthe flow of the gas into its associated line, and mass flow controllersor other types of controllers that measure the flow of gas or liquidthrough the supply lines. Supply lines for each of the gases may alsoinclude concentration monitors for monitoring precursor concentrationsand providing real time feedback. Backpressure regulators may beincluded to control precursor gas concentrations. Valve switchingcontrol may be used for quick and accurate valve switching capability.Moisture sensors in the gas lines measure water levels and can providefeedback to the system software which in turn can providewarnings/alerts to operators. The gas lines may also be heated toprevent precursors and cleaning gases from condensing in the supplylines. Depending upon the process used some of the sources may be liquidrather than gas. When liquid sources are used, the chemical deliverymodule includes a liquid injection system or other appropriate mechanism(e.g., a bubbler) to vaporize the liquid. Vapor from the liquids is thenusually mixed with a carrier gas as would be understood by a person ofskill in the art.

The temperature of the walls of the MOCVD chamber 102 and surroundingstructures, such as the exhaust passageway, may be further controlled bycirculating a heat-exchange liquid through channels (not shown) in thewalls of the chamber 102. The heat-exchange liquid can be used to heator cool the chamber body 202 depending on the desired effect. Forexample, hot liquid may help maintain an even thermal gradient during athermal deposition process, whereas a cool liquid may be used to removeheat from the system during an in-situ plasma process, or to limitformation of deposition products on the walls of the chamber. Thisheating, referred to as heating by the “heat exchanger”, beneficiallyreduces or eliminates condensation of undesirable reactant products andimproves the elimination of volatile products of the process gases andother contaminants that might contaminate the process if they were tocondense on the walls of cool vacuum passages and migrate back into theprocessing chamber during periods of no gas flow.

In one embodiment, during processing, a first precursor gas flows fromthe first processing gas channel 204A in the showerhead assembly 204 anda second precursor gas flows from the second processing gas channel 204Bformed in the showerhead assembly 204 towards the surface of thesubstrates 240. As noted above, the first precursor gas and/or secondprecursor gas may comprise one or more precursor gases or process gassesas well as carrier gases and dopant gases which may be mixed with theprecursor gases. The draw of the exhaust ports 209 may affect gas flowso that the process gases flow substantially tangential to thesubstrates 240 and may be uniformly distributed radially across thesubstrate deposition surfaces in a laminar flow. In one embodiment, theprocessing volume 208 may be maintained at a pressure of about 760 Torrdown to about 80 Torr.

Exemplary showerheads that may be adapted to practice embodimentsdescribed herein are described in U.S. patent application Ser. No.11/873,132, filed Oct. 16, 2007, now published as U.S. 2009-0098276,entitled MULTI-GAS STRAIGHT CHANNEL SHOWERHEAD, U.S. patent applicationSer. No. 11/873,141, filed Oct. 16, 2007, now published as U.S.2009-0095222, entitled MULTI-GAS SPIRAL CHANNEL SHOWERHEAD, and U.S.patent application Ser. No. 11/873,170, filed Oct. 16, 2007, nowpublished as U.S. 2009-0095221, entitled MULTI-GAS CONCENTRIC INJECTIONSHOWERHEAD, all of which are incorporated by reference in theirentireties. Other aspects of the MOCVD chamber 102 are described in U.S.patent application Ser. No. 12/023,520, filed Jan. 31, 2008, publishedas U.S. 2009-0194024, and titled CVD APPARATUS, which is hereinincorporated by reference in its entirety.

In summary, embodiments of the present invention include a showerheadassembly having concentric tube assemblies for separately deliveringprocessing gases into a processing volume of a processing chamber. Theshowerhead assembly further includes one or more cleaning gas conduitsconfigured to bypass the concentric tube assemblies and deliver acleaning gas directly through the showerhead assembly into theprocessing volume of the processing chamber. The showerhead assembly mayalso include a plurality of metrology conduits configured to deliver acleaning gas directly through the showerhead assembly into theprocessing volume of the processing chamber. By delivering the cleaninggas directly through the showerhead and bypassing the processing gasdistribution channels, the components of the processing chamber areefficiently cleaned while reducing scavenging effects associated withdelivering cleaning gases through showerhead processing gas passages.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

The invention claimed is:
 1. A showerhead apparatus, having: a first gaschannel coupled to a first gas inlet; a second gas channel coupled to asecond gas inlet, wherein the first gas channel is isolated from thesecond gas channel; a temperature control channel coupled to a heatexchanging fluid inlet; and a cleaning gas conduit extending through thefirst gas channel, the second gas channel, and the temperature controlchannel, wherein the cleaning gas conduit directly couples a cleaninggas inlet to an exit surface of the showerhead apparatus.
 2. Theapparatus of claim 1, wherein the cleaning gas conduit is a cylindricaltube directly coupling the cleaning gas inlet with the exit surface ofthe showerhead assembly.
 3. The apparatus of claim 2, wherein thecleaning gas conduit is centrally located in the showerhead apparatus.4. The apparatus of claim 3, wherein the first gas inlet is concentricabout the cleaning gas inlet.
 5. The apparatus of claim 1, furthercomprising a plurality of metrology conduits extending through the firstgas channel, the second gas channel, and the temperature controlchannel, wherein each metrology conduit directly couples a metrologyport to the exit surface of the showerhead apparatus.
 6. A showerheadapparatus, having: a first gas channel coupled to a first gas inlet; asecond gas channel coupled to a second gas inlet, wherein the first gaschannel is isolated from the second gas channel; a temperature controlchannel, wherein the temperature control channel is isolated from thefirst and second gas channels; and a cleaning gas conduit extendingthrough the first gas channel, the second gas channel, and thetemperature control channel, wherein the cleaning gas conduit directlycouples a cleaning gas inlet to an exit surface of the showerheadapparatus.
 7. The apparatus of claim 6, wherein the cleaning gas conduitis a cylindrical tube directly coupling the cleaning gas inlet with theexit surface of the showerhead assembly.
 8. The apparatus of claim 7,wherein the cleaning gas conduit is centrally located in the showerheadapparatus.
 9. The apparatus of claim 8, wherein the first gas inlet isconcentric about the cleaning gas inlet.
 10. The apparatus of claim 1,further comprising a plurality of metrology conduits extending throughthe first gas channel, the second gas channel, and the temperaturecontrol channel, wherein each metrology conduit directly couples ametrology port to the exit surface of the showerhead apparatus.
 11. Asubstrate processing apparatus, comprising: a chamber body; a substratesupport; and a showerhead apparatus, wherein a processing volume isdefined by the chamber body, the substrate support, and the showerheadapparatus, and wherein the showerhead apparatus has: a first gas channelcoupled to a first gas inlet; a second gas channel coupled to a secondgas inlet, wherein the first gas channel is isolated from the second gaschannel; a temperature control channel coupled to a heat exchangingfluid inlet; and a cleaning gas conduit extending through the first gaschannel, the second gas channel, and the temperature control channel,wherein the cleaning gas conduit directly couples a cleaning gas inletto the processing volume.
 12. The apparatus of claim 11, wherein thecleaning gas inlet is a tube that directly couples the cleaning gasinlet to the processing volume.
 13. The apparatus of claim 12, whereinthe cleaning gas conduit is centrally located in the showerheadassembly.
 14. The apparatus of claim 11, further comprising a pluralityof metrology conduits extending through the first gas channel, thesecond gas channel, and the temperature control channel, wherein eachmetrology conduit directly couples a metrology port to the processingvolume.
 15. The apparatus of claim 14, wherein each metrology port iscoupled to a metrology assembly and a gas assembly, and wherein each gasassembly is coupled to the cleaning gas source.
 16. The apparatus ofclaim 15, wherein the plurality of metrology conduits are configuredconcentrically about the cleaning gas conduit.